Oxy-bis-(n-alkylamides) and their use as slip additives

ABSTRACT

OXY-BIX-(N-ALKYLAMIDES) HAVING THE FORMULA   R-NH-CO-(CH2)X-O-(CH2)X-CO-NH-R&#39;&#39;   WHEREIN X IS 1 OR 2, R IS AN ALKYL GROUP OF 4 TO 22 CARBON ATOMS AND R&#39;&#39;IS AN ALKYL GROUP OF 4 TO 22 CARBO ATOMS AND COMPOSITIONS COMPRISING (A) POLYETHYLENE, POLYPROPYLENE, COPOLYMERS OF ETHYLENE AND ALPHA-OLEFINS OF MORE THAN 2 CARBON ATOMS, COPOLYMERS OF PROPYLENE AND ALPHA-OLEFINS OF MORE THAN 3 CARBON ATOMS, COPOLYMERS OF ETHYLENE AND VINYL ACETATE CONTAINING UP TO ABOUT 12 PERCENT BY WEIGHT VINYL ACETATE POLYMERIZED UNITS OR MIXTURES THEREOF, AND (B) 300 TO 20,000 P.P.M. BY WEIGHT OF ANY OXY-BIS-(N-ALKYLAMIDE).

United States Patent 3,766,269 OXY-BIS-(N-ALKYLAMIDES) AND THEIR USE ASSLIP ADDITIVES Richard James Powell, Orange, Tex., assignor to E. I. duPont de Nemours and Company, Wilmington, Del. No Drawing. Filed May 11,1971, Ser. No. 142,335 Int. Cl. C07c 103/30 U.S. Cl. 260561 B ClaimsABSTRACT OF THE DISCLOSURE Oxy-bis-(N-alkylamides) having the formulaThis invention relates to oxy-bis-(N-alkylamides). Particularly thisinvention relates to film-forming, carbon chain saturated polymerscontaining oxy-bis-(N-alkylamides).

When a roll of plastic film is unwound or sheets of film are fed from astack of such sheets, it is desirable that there be little cohesion ofthe film to an adjacent layer thereof. One measure of this cohesion iscalled block, which is a measure of the force required to peel one sheetof plastic film from another. Another measure of this cohesion is calledslip, which is a measure of the force required to draw one sheet ofplastic film across another sheet thereof. Generally, a low value forslip and for block means that a low force is required in each of thesetests and therefore that the cohesion is also low. The use of additivesin film resin compositions for the purpose of improving the slip andblock properties of the resultant film is known. Additives which havebeen utilized in polyethylene include oleamide, erucamide, N,N'-dialphatic thiodipropionamide, and stearamide. However, there is still aneed for improved slip and antiblock additives for polyethylene and forother film-forming plastics.

A composition has been found which when incorporated into a film-formingresin yields a resin which produces a film with improved slip and blockproperties. The composition is oxy-bis(N-alkylamide), having the formulawherein x is 1 or 2, R is an alkyl group of 4 to 22 carbon atoms and Ris an alkyl group of 4 to 22 carbon atoms.

When the composition above is incorporated in a filmforming resin, amixture results which comprises (A) a polymer selected from the classconsisting of polyethylene, polypropylene, copolymers of ethylene andalphaolefins of more than two carbon atoms, copolymers of propylene andalpha-olefins of more than three carbon atoms, copolymers of ethyleneand vinyl acetate containing up to about 12 percent by weightpolymerized vinyl ice acetate units, and mixtures thereof and (B) 300 to20,000 p.p.m. by weight of wherein x is 1 or 2, R is an alkyl group of 4to 22 carbon atoms, and R' is an alkyl group of 4 to 22 carbon atoms.

In the oxy-bis-(N-alkylamides), x is preferably 1 while R and R arepreferably 8 to 22 carbon atoms. R and R can be either saturated orunsaturated alkyl groups but the unsaturated alkyl groups are preferred.The R and Rs which are preferred are oleyl, octyl, eru cyl, andcombinations which R is oleyl and R is stearyl and R is eruc'yl and R isbehenyl.

The preferred concentration of the slip additive in the film-formingpolymers is 500 to 2000 p.p.m. by weight. The exact amount of theadditive to be used will depend on the particular additive to beemployed, the particular polymer in which it is utilized, and theresults desired therefrom.

The film-forming polymers in which the additives of the presentinvention are used include linear and branched polyethylene,polypropylene, copolymers of ethylene and alpha-olefins of more than twocarbon atoms such as propylene, copolymers of ethylene and vinyl acetatecontaining up to about 12 percent by weight vinyl acetate polymerizedunits, copolymers of propylene and alpha-olefins of more than threecarbon atoms, and mixtures of the above. The slip additives of thepresent invention can also be utilized in ethylene/methacrylic oracrylic acid copolymers or ionomers thereof.

Other of the conventional compounding additives can be present in themixture of the film-forming resin and the slip additive, such as releaseagents, antioxidants, antistatic and other stabilizers. Also, from 500to 5000 p.p.m of finely-divided silioa can be used together with theoxy-bisd N-alkylamides) to increase the eflectiveness of the additive inhighly glossy films, i.e., films with a gloss greater than 80.

The oxy-bis-(N-alkylamides) of the present invention are prepared bydirect reaction of the appropriate oxy acid such as oxydiacetic acid andappropriate amine.

The oxy-bis-(N-alkylamides) additives of the present invention can beincorporated into the film-forming composition by conventional methodssuch as by injecting the additive into an extruder as a melt or in asolution or dry blending the polymer granules with the additive and thenextruding the blend. Also, a concentrate of the additive in a polymercan be formed and then added to the remainder of the resin via anextruder. Other mixing equipment can be used such as a Banbury Mixer ora roll mill.

The resulting mixture can be subjected to any of the conventionalfilm-forming processes such as blowing, chill rolling, or water bath toform films which are useful for wrapping, etc. and which exhibitimproved slip and blocking properties, generally without sacrificing thevisual characteristics of the film as measured by gloss and haze.

The following examples are meant to illustrate but not limit theinvention. All parts and percentages are by weight unless otherwisespecified. In the examples, the slip coefiicient is determinedsubstantially according to ASTM D-1894-63-Procedure B by using thefollowing procedure: A film-covered metal object, i.e., boat (1.750"diameter), is pulled over a smooth stationary film surface. The metalboat which is pulled over the stationary surface 0 is pulled at aconstant rate (20"/min.) by string running over a strain cell. Thestatic and kinetic forces required to move the boat are registered on arecorder. The coefficient of friction is calculated by dividing theforces parallel to the direction of motion by that perpendicular to thedirection of motion. A set of weights for the boat is used which willprovide a range of total weight perpendicular to the direction of motionof 0.34 pound to 2.14 pounds.

In the examples natural block of blown film is the tendency for theinner surfaces of the collapsed film bubble to stick together. Theprocedure for the test is as follows: A test specimen is carefully cutfrom the roll of blown film as a 2" x 4" piece which has two layers. Atab on one layer is clamped stationary and a tab on the opposite end ofthe other layer is hooked to a string attached to a strain cell. The twolayers of film are separated in the direction of the slip, i.e.,parallel to the film surface. The force in pounds required to separatethe two film layers at a constant rate is read from a recorder inpounds. This value is the force in pounds required to separate a surfaceof 8 square inches.

In the examples, gloss is measured according to ASTM- I Example I Amixture of 13.4 g. of diglycolic acid (oxy-bis-acetic acid) and 37 g. oflaurylamine (molar ratio 1:2) was placed in a 500 ml. beaker and heatedto above the melt ing point. As the temperature was increased, water wasevolved as a vapor. The temperature of the mixture was maintained atabout 175 C. for minutes. The mixture was stirred occasionally duringthe heating period. Gradually the amount. of water vapor evolvingdecreased, and

Example II A copolymer of ethylene and vinyl acetate (5.5 weightpercent) was dry blended with each of the additives shown in Table 1that there was 1000 p.p.m. by weight of each of the additives present.The polymer-additive mixture was melt blended at about 190 C. in a 2" extruder having a length-to-diameter ratio of 20:1 and fitted with amixing torpedo.

The polymer-additive blends were processed into a125- mil blown filmwith a 2 /2" extruder having a length-todiameter ratio of 20:1 andequipped with a 4" diameter die. The film was collapsed on passingthrough a nip roll maintained at 40 psi. The melt temperature of thefilm was about 360 F. Table 1 indicates the various additives utilizedand their respective melting points as well as valves for slip and blockfor each of the films containing these additives.

Example III The procedure of Example II was followed except that thepolymer utilized was a copolymer of ethylene and vinyl acetate (3.8weight percent) and the only additive utilized wasoxy-bis-(N-oleylacetarnide), the additive being present at 1000 p.p.m.by Weight. The results of various physical property tests on the filmare shown in Table 2.

TABLE 2 Physical property:

Haze, percent 3.8 Gloss (20) 94 Slip, lb./lb. a 0.10 Block, lb./8 in.2.17

Example IV The film was prepared utilizing the same procedure and thesame amount of additive and polymer as in Example II. The slip additiveutilized was oxy-bis-(N-oleylacet amide). In this case, however, silicawas also added to the blend before it was formed into a film. The amounta of silica utilized is shown in Table 3. The results of slip and blocktests on the film as a function of time and silica content are shown inTable 3.

Following the procedure of Example II, two films were prepared whichwere 1.25 mils thick. The first film was made from polyethylene whichcontained 1000 parts per million by weight oxy-bis-(N-o'leylacetamide)and the second film was made from polyethylene which contained 1000parts per million by weight oxy-bis-(N-oleylacetamide) and 550 parts permillion by weight silica. Both films had a slip coefficient of less than0.1 lb./lb. while the block value for both films was less than 0.1 lb./8 in.*.

Example VI TABLE 4 Amount, Haze, Block, p.p.m. by Gloss per- Slip, lh./8Additive weight (20) cent 1b./lb. 1n.

None 0 16 11. 5 0. 99 0. 91 Dry bis (N octylaeeta- V mide) 1, 000 13 120. 08 0. 47 14 0. 08 0. 46

Example VII' Following the procedure of Example II, a 1.25 mil blownfilm was preparedon a 1 /2" extruder which had a 16:1 length-to-diameterratio and was equipped with a 4" diameter die. The film was preparedfrom an ethylene/ propylene (approximately 1-3 percent by weight)copolymer with a melt index of 2.6 g./ 10 min. and a density of 0.921gram/cc. which contained 1000 parts per million by weightoxy-bis(N-octylpropionamide) The film had a gloss (20) of 98, a haze of4.3 percent, a slip of 0.36 lb./1b. and a block of 0.79 1b'./8 in.

Example VIII Following the procedure of Example I, oxy-bis-(N-octylacetamide) was prepared from a mixture of 13.4 g. of diglycolicacid and 25.8 g. of octylamine (molar ratio of 1:2).

Example IX Following the procedure of Example I, oxy-bis-(N-oleylacetamide) was prepared from a mixture of 13.4 g. of diglycolicacid and 50.3 g. of oleylamine (molar ratio of 1:2).

Example X 7; 7; I N R It wherein an is 1 or 2, R is an alkyl group offrom 4 to 22 carbon atoms, and R is an alkyl group of 4 to 22 carbonatoms.

2. The composition of claim 1 wherein x is 1 and R is an alkyl group of8 to 22 carbon atoms and R is an alkyl group of 8 to 22 carbon atoms.

3. The composition of claim 2 wherein R is selected from the groupconsisting of oleyl, octyl and erucyl and R is selected from the groupconsisting of oleyl, octyl and erucyl.

4. The composition of claim 1 wherein R is oleyl and R is stearyl.

5. The composition of claim 1 wherein R is erucyl and R is behenyl.

References Cited UNITED STATES PATENTS 2,158,064 5/1939 Carothers 26056lK X 2,594,286 4/1952 Bryant et al. 260-561 K X 3,320,315 5/1967 Towle eta1 260-561 K OTHER REFERENCES Christian, Jr., et al., Iourn. Amer. Chem.800., pp. 1333-6, vol. 70.

LEWIS GOTIS, Primary Examiner E. G. LOVE, Assistant Examiner US. Cl.X.R. 260-32.6, 561 K a -4 3 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 5,766,269 Dated October 16, 1975 Inventor(s)Richard James Powell It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

{- Column 1, line 27, "any" should read an Column 2, line 16, "which"should read where Column 3, line A6, after "Table 1", insert such ColumnA, line an, "0.1" should read 0.5

Signed and sealed this 23rd day of April 1971+.

(SEAL) Attest:

EDWARD 1'-'I.FLl5TCHER,JR. C. MARSHALL DANN Attesting fficerCommissioner of Patents

